ABSTRACT: PURPOSE:Blood/saliva DNA is thought to represent the germ line in genetic cancer-risk assessment. Cases with pathogenic TP53 variants detected by multigene panel testing are often discordant with Li-Fraumeni syndrome, raising concern about misinterpretation of acquired aberrant clonal expansions (ACEs) with TP53 variants as germ-line results. METHODS:Pathogenic TP53 variants with abnormal next-generation sequencing metrics (e.g., decreased ratio (<25%) of mutant to wild-type allele, more than two detected alleles) were selected from a CLIA laboratory testing cohort. Alternate tissues and/or close relatives were tested to distinguish between ACE and germ-line status. Clinical data and Li-Fraumeni syndrome testing criteria were examined. RESULTS:Among 114,630 multigene panel tests and 1,454 TP53 gene-specific analyses, abnormal next-generation sequencing metrics were observed in 20% of 353 TP53-positive results, and ACE was confirmed for 91% of cases with ancillary materials, most of these due to clonal hematopoiesis. Only four met Chompret criteria. Individuals with ACE were older (50 years vs. 33.7; P?=?0.02) and were identified more frequently in multigene panel tests (66/285; 23.2%) than in TP53 gene-specific tests (6/68; 8.8%, P?=?0.005). CONCLUSION:ACE confounds germ-line diagnosis, may portend hematologic malignancy, and may provoke unwarranted clinical interventions. Ancillary testing to confirm germ-line status should precede Li-Fraumeni syndrome management.
Project description:Next-generation sequencing (NGS)-based targeted gene capture panels are used to profile hematopoietic malignancies to guide prognostication and treatment decisions. Because these panels include genes associated with hereditary hematopoietic malignancies (HHMs), we hypothesized that these panels could identify pathogenic germ line variants in malignant cells, thereby identifying patients at risk for HHMs. In total, pathogenic or likely pathogenic variants in ANKRD26, CEBPA, DDX41, ETV6, GATA2, RUNX1, or TP53 were identified in 74 (21%) of 360 patients. Germ line tissue was available for 24 patients with 25 pathogenic or likely pathogenic variants with variant allele frequencies >0.4. Six (24%) of these 25 variants were of germ line origin. Three DDX41 variants, 2 GATA2 variants, and a TP53 variant previously implicated in Li-Fraumeni syndrome were of germ line origin. No likely pathogenic/pathogenic germ line variants possessed variant allele frequencies <0.4. This study demonstrates that NGS-based prognostic panels may identify individuals at risk for HHMs despite not being designed for this purpose. Furthermore, variants known to cause Li-Fraumeni syndrome as well as known pathogenic variants in genes such as DDX41 and GATA2 are especially likely to be of germ line origin. Thus, tumor-based panels may augment, but should not replace, comprehensive germ line-based testing and counseling.
Project description:Although rare, adrenocortical carcinoma is among the most common tumors found in children with Li-Fraumeni syndrome and Li-Fraumeni-like syndrome, associated with germ-line mutations in the TP53 gene. In southern Brazil, one form of Li-Fraumeni syndrome, associated with childhood adrenocortical carcinoma, is caused by a mutation in the R337H TP53 tetramerisation domain and is attributed to a familial founder effect. Adrenocortical carcinoma is considered an aggressive neoplasm, usually of poor prognosis and is generally unresponsive to systemic chemotherapy. Optimal treatment regimens remain to be established. We report the case of a young woman with metastatic adrenocortical carcinoma, who achieved stable disease with mitotane, cisplatin, doxorubicin, and etoposide as first-line therapy, but then had an objective response to oral metformin that lasted 9?months. The presence of the R337H TP53 mutation suggests a mechanism for the observed response to metformin.
Project description:The TP53 tumor-suppressor gene is mutated in >50% of human tumors and Li-Fraumeni patients with germ line inactivation are predisposed to developing cancer. Here, we generated tp53 deleted zebrafish that spontaneously develop malignant peripheral nerve-sheath tumors, angiosarcomas, germ cell tumors, and an aggressive Natural Killer cell-like leukemia for which no animal model has been developed. Because the tp53 deletion was generated in syngeneic zebrafish, engraftment of fluorescent-labeled tumors could be dynamically visualized over time. Importantly, engrafted tumors shared gene expression signatures with predicted cells of origin in human tissue. Finally, we showed that tp53del/del enhanced invasion and metastasis in kRASG12D-induced embryonal rhabdomyosarcoma (ERMS), but did not alter the overall frequency of cancer stem cells, suggesting novel pro-metastatic roles for TP53 loss-of-function in human muscle tumors. In summary, we have developed a Li-Fraumeni zebrafish model that is amenable to large-scale transplantation and direct visualization of tumor growth in live animals.
Project description:BACKGROUND: Germ-line mutations of the TP53 gene are known to cause Li-Fraumeni syndrome, an autosomal, dominantly inherited, high-penetrance cancer-predisposition syndrome characterized by the occurrence of a variety of cancers, mainly soft tissue sarcomas, adrenocortical carcinoma, leukemia, breast cancer, and brain tumors. METHODS: Mutation analysis was based on Denaturing high performance liquid chromatography (DHPLC) screening of exons 2-11 of the TP53 gene, sequencing, and cloning of DNA obtained from peripheral blood lymphocytes. RESULTS: We report herein on Li Fraumeni syndrome in a family whose members are carriers of a novel TP53 gene mutation at exon 4. The mutation comprises an insertion/duplication of seven nucleotides affecting codon 110 and generating a new nucleotide sequence and a premature stop codon at position 150. With this mutation, the p53 protein that should be translated lacks the majority of the DNA binding domain. CONCLUSION: To our knowledge, this specific alteration has not been reported previously, but we believe it is the cause of the Li-Fraumeni syndrome in this family.
Project description:BACKGROUND:Breast cancer is the most prevalent tumor entity in Li-Fraumeni syndrome. Up to 80% of individuals with a Li-Fraumeni-like phenotype do not harbor detectable causative germline TP53 variants. Yet, no systematic panel analyses for a wide range of cancer predisposition genes have been conducted on cohorts of women with breast cancer fulfilling Li-Fraumeni(-like) clinical diagnostic criteria. METHODS:To specifically help explain the diagnostic gap of TP53 wild-type Li-Fraumeni(-like) breast cancer cases, we performed array-based CGH (comparative genomic hybridization) and panel-based sequencing of 94 cancer predisposition genes on 83 breast cancer patients suggestive of Li-Fraumeni syndrome who had previously had negative test results for causative BRCA1, BRCA2, and TP53 germline variants. RESULTS:We identified 13 pathogenic or likely pathogenic germline variants in ten patients and in nine genes, including four copy number aberrations and nine single-nucleotide variants or small indels. Three patients presented as double-mutation carriers involving two different genes each. In five patients (5 of 83; 6% of cohort), we detected causative pathogenic variants in established hereditary breast cancer susceptibility genes (i.e., PALB2, CHEK2, ATM). Five further patients (5 of 83; 6% of cohort) were found to harbor pathogenic variants in genes lacking a firm association with breast cancer susceptibility to date (i.e., Fanconi pathway genes, RECQ family genes, CDKN2A/p14ARF, and RUNX1). CONCLUSIONS:Our study details the mutational spectrum in breast cancer patients suggestive of Li-Fraumeni syndrome and indicates the need for intensified research on monoallelic variants in Fanconi pathway and RECQ family genes. Notably, this study further reveals a large portion of still unexplained Li-Fraumeni(-like) cases, warranting comprehensive investigation of recently described candidate genes as well as noncoding regions of the TP53 gene in patients with Li-Fraumeni(-like) syndrome lacking TP53 variants in coding regions.
Project description:Li-Fraumeni syndrome, usually characterized by germline TP53 mutations, is associated with markedly elevated lifetime risks of multiple cancers, and has been linked to an increased risk of early-onset colorectal cancer.To examine the frequency of germline TP53 alterations in patients with early-onset colorectal cancer.This was a multicenter cross-sectional cohort study of individuals recruited to the Colon Cancer Family Registry (CCFR) from 1998 through 2007 (genetic testing data updated as of January 2015). Both population-based and clinic-based patients in the United States, Canada, Australia, and New Zealand were recruited to the CCFR. Demographic information, clinical history, and family history data were obtained at enrollment. Biospecimens were collected from consenting probands and families, including microsatellite instability and DNA mismatch repair immunohistochemistry results. A total of a 510 individuals diagnosed as having colorectal cancer at age 40 years or younger and lacking a known hereditary cancer syndrome were identified from the CCFR as being potentially eligible. Fifty-three participants were excluded owing to subsequent identification of germline mutations in DNA mismatch repair genes (n?=?47) or biallelic MUTYH mutations (n?=?6).Germline sequencing of the TP53 gene was performed. Identified TP53 alterations were assessed for pathogenicity using literature and international mutation database searches and in silico prediction models.Frequency of nonsynonymous germline TP53 alterations.Among 457 eligible participants (314, population-based; 143, clinic-based; median age at diagnosis, 36 years [range, 15-40 years]), 6 (1.3%; 95% CI, 0.5%-2.8%) carried germline missense TP53 alterations, none of whom met clinical criteria for Li-Fraumeni syndrome. Four of the identified TP53 alterations have been previously described in the literature in probands with clinical features of Li-Fraumeni syndrome, and 2 were novel alterations.In a large cohort of patients with early-onset colorectal cancer, germline TP53 mutations were detected at a frequency comparable with the published prevalence of germline APC mutations in colorectal cancer. With the increasing use of multigene next-generation sequencing panels in hereditary cancer risk assessment, clinicians will be faced with the challenge of interpreting the biologic and clinical significance of germline TP53 mutations in families whose phenotypes are atypical for Li-Fraumeni syndrome.
Project description:PURPOSE:The TP53 tumor suppressor gene encodes a sequence-specific transcription factor that is able to transactivate several sets of genes, the promoters of which include appropriate response elements. Although human cancers frequently contain mutated p53, the alleles as well as the clinical expression are often heterogeneous. Germ line mutations of TP53 result in cancer proneness syndromes known as Li-Fraumeni, Li-Fraumeni--like, and nonsyndromic predisposition with or without family history. p53 mutants can be classified as partial deficiency alleles or severe deficiency alleles depending on their ability to transactivate a set of human target sequences, as measured using a standardized yeast-based assay (see http://www.umd.be:2072/index.html). We have investigated the extent to which the functional features of p53 mutant alleles determine clinical features in patients who have inherited these alleles and have developed cancer. EXPERIMENTAL DESIGN:We retrieved clinical data from the IARC database (see http://www.p53.iarc.fr/Germline.html) for all cancer patients with germ line p53 mutations and applied stringent statistical evaluations to compare the functional classification of p53 alleles with clinical phenotypes. RESULTS:Our analyses reveal that partial deficiency alleles are associated with a milder family history (P = 0.007), a lower numbers of tumors (P = 0.007), and a delayed disease onset (median, 31 versus 15 years; P = 0.007) which could be related to distinct tumor spectra. CONCLUSIONS:These findings establish for the first time significant correlations between the residual transactivation function of individual TP53 alleles and clinical variables in patients with inherited p53 mutations who develop cancer.
Project description:BACKGROUND:Li-Fraumeni syndrome is a cancer predisposition syndrome caused by germline TP53 tumor suppressor gene mutations, with no previous association with pancreatic neuroendocrine tumors (PNETs). Here we present the first case of PNET associated with Li-Fraumeni syndrome. CASE PRESENTATION:This is a 43-year-old female who underwent laparoscopic distal pancreatectomy at age 39 for a well-differentiated grade 2 cystic PNET. When the patient was 41?years old, her seven-year-old daughter was found to have an astrocytoma and a germline TP53 mutation. While undergoing surveillance with 68Gallium-DOTATATE positron emission tomography/computed tomography for her PNET, the patient was found to have a large choroid plexus papilloma in her right temporal lobe. She underwent genetic counseling and testing that identified a germline pathogenic variant in TP53, leading to the diagnosis of Li-Fraumeni syndrome. Her PNET had a hemizygous pathogenic TP53 mutation with loss of the wild-type alternate allele, consistent with loss of heterozygosity and the two-hit hypothesis. She was enrolled in a Li-Fraumeni syndrome protocol and continues surveillance screening with our service. CONCLUSIONS:This is the first PNET reported in association with Li-Fraumeni syndrome. Pancreatic cancer risk is elevated in this syndrome, and our case highlights the need for vigilance in screening for pancreatic neoplasms in these patients.
Project description:Li-Fraumeni syndrome (LFS) is a rare familial cancer syndrome characterized by early cancer onset, diverse tumor types, and multiple primary tumors. Germ-line TP53 mutations have been identified in most LFS families. A high-frequency single-nucleotide polymorphism, SNP309 (rs2279744), in MDM2 was recently confirmed to be a modifier of cancer risk in several case-series studies: substantially earlier cancer onset was observed in SNP309 G-allele carriers than in wild-type individuals by 7-16 years. However, cancer risk analyses that jointly account for measured hereditary TP53 mutations and MDM2 SNP309 have not been systematically investigated in familial cases. Here, we determined the combined effects of measured TP53 mutations, MDM2 SNP309, and gender and their interactions simultaneously in LFS families. We used the method that is designed for extended pedigrees and structured for age-specific risk models based on Cox proportional hazards regression. We analyzed the cancer incidence in 19 extended pedigrees with germ-line TP53 mutations ascertained through the clinical LFS phenotype. The dataset consisted of 463 individuals with 129 TP53 mutation carriers. Our analyses showed that the TP53 germ-line mutation and its interaction with gender were strongly associated with familial cancer incidence and that the association between MDM2 SNP309 and increased cancer risk was modest. In contrast with several case-series studies, the interaction between MDM2 SNP309 and TP53 mutation was not statistically significant in our LFS family cohort. Our results showed that SNP309 G-alleles were associated with accelerated tumor formation in both carriers and non-carriers of germ-line TP53 mutations.
Project description:Although multiple predispositions to hematologic malignancies exist, evaluations for hereditary cancer syndromes (HCS) are underperformed by most hematologist/oncologists. Criteria for initiating HCS evaluation are poorly defined, and results of genetic testing for hereditary hematologic malignancies have not been systematically reported.From April 2014 to August 2015, 67 patients were referred to the Hereditary Hematologic Malignancy Clinic (HHMC). Referral reasons included (1) bone marrow failure or myelodysplastic syndrome in patients ? 50 years, (2) evaluation for germ-line inheritance of identified RUNX1, GATA2, or CEBPA mutations on targeted next-generation sequencing panels, and (3) strong personal and/or family history of malignancy. Cultured skin fibroblasts were utilized for germ-line DNA in all patients with hematologic malignancy.Eight patients (12%) were clinically diagnosed with a HCS: 4 patients with RUNX1-related familial platelet disorder (FPD)/acute myeloid leukemia (AML), and 1 patient each with dyskeratosis congenita, Fanconi anemia, germ-line DDX41, and Li-Fraumeni syndrome (LFS). Two patients with concern for FPD/AML and LFS, respectively, had RUNX1 and TP53 variants of unknown significance. Additionally, 4 patients with prior HCS diagnosis (1 LFS, 3 FPD/AML) were referred for further evaluation and surveillance.In this HHMC-referred hematologic malignancy cohort, HCS was confirmed in 12 patients (18%). HCS identification provides insight for improved and individualized treatment, as well as screening/surveillance opportunities for family members. The HHMC has facilitated HCS diagnosis; with increased clinical awareness of hematologic malignancy predisposition syndromes, more patients who may benefit from evaluation can be identified. Mutation panels intended for prognostication may provide increased clinical suspicion for germ-line testing.